Using urea-dentured ovalbumin for carrier-priming, effect of carrier-primed T cells on the development of IgE-B memory cells will be studied in the mouse. Carrier-specific T cells will be primed either by alum-absorbed carrier or by carrier alone. Both the helper activity of the carrier-primed cells and their enhancing effect on the development of B memory cells will be evaluated. The possibility is considered that carrier-primed T cells may affect the distribution of B memory cells for different isotypes. In high responder strain mice, a persistent IgE and IgG antibody formation is obtained by the immunization with a minute dose of alum-absorbed antigen. Since the regulation of such a persistent antibody formation is essential for depression of the IgE antibody formation in atopic patients, we shall analyze the mechanisms and immunocompetent cells involved in the persistent antibody formation. Using the mesenteric lymph node cells from rats infected with Nippostrongylus brasiliensis, T cells and T cell factors involved in the in vitro IgE response will be analyzed.